调查幼年型髓系-单核细胞性白血病（JMML）的临床特征及其与预后的相关性。收集2008 年1 月至2016 年12 月收治的JMML 患儿的临床和预后数据，并分析影响预后的因素。共纳入63 名JMML 患儿，中位发病年龄为25 个月，男女比例为3.2∶1。54 名儿童进行了JMML 基因检测，其中PTPN11 突变最常见，23 名患儿（43%）具有该突变，其中19 名仅有PTPN11 突变，4 名有复合PTPN11 突变；NRAS 突变在14 名患儿（26%）中观察到，其中12 名仅有NRAS 突变，2 名有复合NRAS 突变。这些患有JMML 的儿童5 年总生存（OS）率仅为22%±10%。63 名患儿中，13 名（21%）接受了造血干细胞移植（HSCT）。HSCT 组5 年总生存率明显高于非HSCT 组（46%±14% 对29%±7%，P<0.05）。没有PTPN11 基因突变和有PTPN11 基因突变的患儿5 年总生存率之间没有显著差异（30%±14% 对27%±10%，P>0.05）。Cox 比例风险回归模型分析表明，诊断时血小板计数＜40×109/L 是影响JMML 患儿5 年总生存率的因素（P<0.05）。JMML 中PTPN11 基因是最常见的突变基因。发病时的血小板计数与JMML 患儿的预后有关。HSCT 可以改善JMML 患儿的预后。

To investigate the clinical features of juvenile myelomonocytic leukemia (JMML) and their association with prognosis.Clinical and prognosis data were collected from the children with JMML who were admitted from January 2008 to December 2016, and the influencing factors for prognosis were analyzed.A total of 63 children with JMML were included, with a median age of onset of 25 months and a male/female ratio of 3.2∶1. JMML genetic testing was performed for 54 children, and PTPN11 mutation was the most common mutation and was observed in 23 children (43%), among whom 19 had PTPN11 mutation alone and 4 had compound PTPN11 mutation, followed by NRAS mutation observed in 14 children (26%), among whom 12 had NRAS mutation alone and 2 had compound NRAS mutation. The 5-year overall survival (OS) rate was only 22%±10% in these children with JMML. Of the 63 children, 13 (21%) underwent hematopoietic stem cell transplantation (HSCT). The HSCT group had a significantly higher 5-year OS rate than the non-HSCT group (46%±14% vs 29%±7%, P<0.05). There was no significant difference in the 5-year OS rate between the children without PTPN11 gene mutation and those with PTPN11 gene mutation (30%±14% vs 27%±10%, P>0.05). The Cox proportional-hazards regression model analysis showed that platelet count <40×109/L at diagnosis was an influencing factor for 5-year OS rate in children with JMML (P<0.05).The PTPN11 gene was the most common mutant gene in JMML. Platelet count at diagnosis is associated with the prognosis in children with JMML. HSCT can improve the prognosis of children with JMML.